5-Benzofuranyl esters as herbicides and plant growth regulants

ABSTRACT

5-Benzofuranyl esters of the general formula ##STR1## wherein the substituents are as defined in the specification, possess physiological activity, particularly plant physiological activity and may be used as herbicides, plant growth regulants, fungicides, insecticides and anthelmintics.

This application is a continuation in part application of application Ser. No. 275256, filed July 26th 1972 (now abandoned), which is a divisional application of application Ser. No. 826,274, filed May 20th 1969, now U.S. Pat. No. 3689507.

The present invention relates to certain new 5-benzofuranyl esters which have been found to possess physiological activity, particularly plant physiological activity, to their preparation and to agricultural and other compositions containing the same. These compounds may be used as herbicides and as plant growth regulants. The compounds may also be used as fungicides, insecticides and an thelmintics.

Accordingly the present invention is for the 5-benzofuranyl esters of the general formula: ##STR2## wherein R¹, R² and R³ are the same or different and may be hydrogen or alkyl (for example of 1-6 carbon atoms such as methyl or ethyl), or R¹ and R² together or R² and R³ together may form an alkylene chain (for example of 2-5 carbon atoms); R⁴ is hydroxy, alkoxy (for example of 1-8 carbon atoms such as methoxy or butoxy), substituted alkoxy (for example of 1-8 carbon atoms substituted by halogen or alkoxy such as chloroethoxy or methoxyethoxy), alkenyloxy (for example of 2-4 carbon atoms such as allyloxy), alkylthio (for example of 1-4 carbon atoms such as methylthio or ethylthio), substituted alkenyloxy (for example of 2-4 carbon atoms substituted by halogen such as chloroallyloxy), alkynyloxy (for example of 2-6 carbon atoms such as propargyloxy or butynyloxy), substituted alkynyloxy (for example of 2-4 carbon atoms substituted by halogen such as chlorobutynyloxy), aryloxy (for example phenoxy), substituted aryloxy (for example substituted by nitro or halogen such as nitrophenoxy), the group NR⁶ R⁷ in which R⁶ and R⁷ are alkyl (for example of 1-4 carbon atoms such as methyl or ethyl) or substituted alkyl (for example of 1-4 carbon atoms substituted by halogen such as haloethyl) or together with the nitrogen atom form a heterocyclic ring, substituted or unsubstituted such as morpholine, pyrrolidine, piperidine or methyl piperazine, the group --OCOR¹³, the group --OSO₂ R¹⁴ or the group --O-O-R¹⁵, in which R¹³ is alkyl (for example of 1-4 carbon atoms such as methyl or isopropyl), alkenyl (for example of 2-4 carbon atoms such as allyl), alkynyl (for example of 2-4 carbon atoms such as propargyl), substituted alkyl, alkenyl or alkynyl (for example aryloxy or halogen substituted such as trifluoromethyl, phenoxymethyl or chloroethyl), aryl (for example phenyl), substituted aryl (for example halogen or alkyl substituted such as chlorophenyl or tolyl), alkylamino (for example of 1-4 carbon atoms such as methylamino), dialkylamino (for example of 2-8 carbon atoms such as dimethylamino), alkoxy (for example of 1-6 carbon atoms such as methoxy or ethoxy), aryloxy (for example phenoxy), arylamino (for example phenylamino), substituted arylamino (for example substituted by halogen such as chlorophenylamino), substituted alkoxy (for example of 1-6 carbon atoms substituted by halogen or alkoxy such as methoxyethoxy), substituted aryloxy (for example halogen substituted such as chlorophenoxy), alkenyloxy (for example of 2-4 carbon atoms such as allyloxy), substituted alkenyloxy (for example of 2-4 carbon atoms substituted by halogen such as chloroallyloxy), alkynyloxy (for example of 2-4 carbon atoms such as propargyloxy) or substituted alkynyloxy (for example of 2-4 carbon atoms substituted by halogen such as chlorobutynyloxy), in which R¹⁴ is alkyl (for example of 1-4 carbon atoms such as methyl or ethyl), substituted alkyl (for example of 1-4 carbon atoms substituted by halogen such as chloroethyl), aryl (for example phenyl), substituted aryl (for example halogen, nitro or alkyl substituted such as chlorophenyl, nitrophenyl or tolyl), in which R¹⁵ is alkyl (for example of 1-4 carbon atoms such as methyl, isopropyl or tertiary butyl), alkenyl (for example of 2-4 carbon atoms such as allyl) or alkynyl (for example of 2-4 carbon atoms such as propargyl); or R³ and R⁴ together represent an oxygen atom or the group ═NR¹⁶ in which R¹⁶ is alkyl (for example of 1-4 carbon atoms such as methyl or isopropyl) or cycloalkyl (for example of 5 or 6 carbon atoms such as cyclohexyl); R⁵ is the group R⁸ CO- or the group R⁹ SO₂ -- or the group R⁹ S0-- in which R⁸ is halogen substituted alkyl (for example of 1-4 carbon atoms such as chloromethyl, dichloroethyl, trichloroethyl or bromoethyl) and R⁹ is alkyl (for example of 1-4 carbon atoms such as methyl or ethyl), substituted alkyl (for example of 1-4 carbon atoms substituted by halogen or alkoxy such as chloromethyl, methoxypropyl and bromoethyl) aryl (for example phenyl) or substituted aryl (for example substituted halogen or alkyl such as chlorophenyl or tolyl); and R¹⁰, R¹¹ and R¹² are the same or different and are hydrogen, alkyl (for example of 1-4 carbon atoms such as methyl, ethyl or isopropyl), halogen (for example chlorine or bromine), cyano, acyl (for example of 2-6 carbon atoms such as acetyl) or alkoxy (for example of 1-4 carbon atoms such as methoxy).

The present invention is also for a physiological active composition and particularly a herbicidal composition or plant growth composition which contains as an active component a benzofuranyl ester as identified above. The physiologically active composition suitably also contains at least one material selected from the group comprising carriers, wetting agents, inert diluents and solvents.

The present invention is also for the treatment of plants, the soil, land or aquatic areas, or materials which comprises applying thereof or thereto a benzofuranyl ester or a plant physiologically active composition as identified above.

The substituted benzofuranyl esters according to the present invention generally possess physiological activity. These compounds are useful as herbicides,and also as plant growth regulants. They are also fungicides, insecticides and anthelmintics.

The benzofuranyl esters identified above have been found to be of particular value as selective herbicides for pre-emergence use and also are useful for post-emergence use. With some crops, pre-emergence use is of greater importance. At higher concentrations the compounds may also be used as total weedkillers. At much lower concentrations the compounds may be used as plant growth regulants.

According to a preferred embodiment the present invention is for the benzofuranyl esters of the general formula: ##STR3## wherein R²⁰ is selected from dialkylamino of 2-4 carbon atoms, piperidino, morpholino, 4-methylpiperazino, pyrrolidino, hydroxy, alkoxy, of 1-4 carbon atoms, alkenyloxy of 2-4 carbon atoms, alkynyloxy of 2-4 carbon atoms, alkoxyalkoxy, of 2-8 carbon atoms, alkylthio of 1-4 carbon atoms, --OCOR²⁸, --SO₂ R²⁹ and --O--O-R²⁹, where R²⁸ is alkyl of 1-4 carbon atoms or phenyl; where R²⁹ is alkyl of 1-4 carbon atoms; where R²¹ is hydrogen or together with R²⁰ represents an oxygen atom, where R²² and R²³ represent hydrogen or alkyl of 1-4 carbon atoms; where R²⁵ represents R³⁰ SO₂ -- where R³⁰ is alkyl of 1-4 carbon atoms; and where R²⁴, R²⁶ and R²⁷ represent hydrogen, halogen (for example chloro or bromo) or alkyl of 1-4 carbon atoms.

According to one embodiment, the present invention is for the benzofuranyl esters according to the general formula above in which R¹, R² and R³ are selected from hydrogen and alkyl, or R¹ and R² together or R² and R³ together form an alkylene chain; where R⁴ is hydroxy, alkoxy, substituted alkoxy, alkenyloxy, alkylthio or --NR⁶ R⁷, and wherein R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹ and R¹² have the significance indicated above.

According to another embodiment, the present invention is for the benzofuranyl esters according to the general formula above in which R¹, R² and R³ are selected from hydrogen and alkyl, or R¹ and R² together or R² and R³ together form an alkyene chain; where R⁴ is --OCOR¹³ or --OSO₂ R¹⁴, and wherein R⁵, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴ have the significance indicated above.

According to another embodiment, the present invention is for the benzofuranyl esters according to the general formula above in which R¹, R² and R³ are selected from hydrogen and alkyl, or R¹ and R² together or R² and R³ together form an alkylene chain; where R⁴ is the group --O--O--R¹⁵, or R³ and R⁴ together represent an oxygen atom or the group ═NR¹⁶ ; wherein R⁵, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹⁵ and R¹⁶ have the significance indicated above.

The 5-benzofuranyl esters according to the present invention may be prepared by the reaction between the corresponding 5-hydroxybenzofuran of the formula: ##STR4## and an acylating agent of the formula R⁵ X or (R⁵)₂ O where X is halogen, particularly chlorine. The reaction is preferably carried out in the presence of an acid acceptor such as an organic base (for example pyridine or triethylamine) or an alkali (for example an alkali metal carbonate or bicarbonate).

The benzofuranyl esters where R⁴ is the group --OCOR¹³ or --OSO₂ R¹⁴ may be prepared by reacting the corresponding compound where R⁴ is hydroxy, with a compound of the formula R¹³ COX or R¹⁴ SO₂ X (in which X is halogen), the groups R¹ -R¹⁴ having the significance indicated above. In the case where R¹³ is a hydrocarbon group, the compound R¹³ COX is an acyl halide and the product is a 2-acyloxybenzofuran; in the case where R¹³ is a substituted amino group, the compound R¹³ COX is a substituted carbamoylhalide and the product is a 2-carbamoyloxybenzofuran; in the case where R¹³ is an alkoxy group or aryloxy group, the compound R¹³ COX is a haloformate and the product is a carbonate ester.

Where R¹³ is an alkylamino group, the compounds can also be prepared by the reaction between a 2-hydroxybenzofuran of the formula above and an alkyl isocyanate.

Where R¹³ is a hydrocarbon group, the compounds can also be prepared by the reaction of a 2-hydroxybenzofuran of the above formula or a corresponding 2-alkoxybenzofuran with an acid anhydride of the formula (R¹³ CO)₂ O.

The benzofuranyl esters where R⁴ is the group --O--O--R¹⁵ may be prepared by reacting the corresponding compound where R⁴ is hydroxy, with a hydroperoxide of the formula R¹⁵ OOH.

The benzofuranyl esters where R³ and R⁴ together represent the group ═NR¹⁶ may be prepared by reacting a ketenimine with a benzoquinone to form the 2-imino-5-hydroxybenzofuran according to the equation: ##STR5## which is then reacted with the compound of the formula R⁵ Cl to give the desired compound.

The benzofuranyl esters where R³ and R⁴ together represent an oxygen atom may be prepared by the oxidation of the corresponding compound where R³ is hydrogen and R⁴ is hydroxy, alkoxy, --NR⁶ R⁷ or --OCOR¹³ (where R⁶ and R⁷ are alkyl, substituted alkyl or heterocyclic and R¹³ is alkyl, alkenyl or alkynyl, substituted or unsubstituted), for example using chromic oxide in acid, or by the hydrolysis of the corresponding compound in which R³ and R⁴ together represent ═NR¹⁶.

The benzofuranyl compounds are generally water insoluble and may be formulated in any of the conventional ways for insoluble compounds.

If desired the benzofuranyl esters may be dissolved in a water immiscible solvent, such as for example a high boiling hydrocarbon, suitably containing dissolved emulsifying agents so as to act as a self-emulsifiable oil on addition to water.

The benzofuranyl esters may also be admixed with a wetting agent with or without an inert diluent to form a wettable powder which is soluble or dispersable in water, or may be mixed with the inert diluent to form a solid or powdery product.

Inert diluents with which the benzofuranyl esters may be incorporated include solid inert media comprising powdered or divided solid materials, for example, clays, sands, talc, mica, peat, fertilizers and the like, such products either comprising dust or larger particle size materials such as granules.

The wetting agents used may comprise anionic compounds such as for example soaps, fatty sulphate esters such as dodecyl sodium sulphate, octadecyl sodium sulphate and cetyl sodium sulphate, fatty aromatic sulphonates such as alkylbenzene sulphonates or butyl naphthalene sulphonate, more complex fatty sulphonates such as the amide condensation product of oleic acid and N-methyl taurine or the sodium sulphonate or dioctyl succinate.

The wetting agents may also comprise non-ionic wetting agents such as for example condensation products of fatty acids, fatty alcohols or fatty substituted phenols with ethylene oxide, or fatty esters and others of sugars or polyhydric alcohols, or the products obtained from the latter by condensation with ethylene oxide, or the products known as block copolymers of ethylene oxide and propylene oxide. The wetting agents may also comprise cationic agents such as for example cetyl trimethylammonium bromide and the like.

The physiologically active compositions according to the present invention may contain in addition to the benzofuranyl esters, other physiologically active materials such as herbicides, insecticides, fungicides and molluscicides. It has been found that particular advantages are obtained with mixtures with other herbicides.

Accordingly, a further embodiment of the present invention is for a herbicidal composition which comprises a mixture of the benzofuranyl esters as identified above and a second herbicide.

The second herbicide may be for example a phenoxyaliphatic acid, substituted urea, triazine, phenol, nitrile, bipyridylium compound, substituted benzoic acid, halogenated aliphatic acid, carbonate, thiocarbonate, chloroacetanide, diazine, arsenic compound or other herbicidal compound. In respect of selective herbicidal compositions for post-emergence use, the second herbicide is preferably a substituted phenoxyaliphatic acid; in respect of selective herbicidal compositions for pre-emergence use, the second herbicide is preferably a substituted urea or triazine.

The phenoxyaliphatic acid generally comprises alkyl and/or halogen substituted phenoxyaliphatic acids, and their salts, for example alkali metal, amine and alkanolamine salts, and functional derivatives, for example esters and amides. These compounds may be of activity such that they are recognised as commercial herbicides, or may be of only slight herbicidal activity. Examples of the substituted phenoxyaliphatic acids which may be mentioned include 2,4-dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid; 2,4,5-trichlorophenoxyacetic acid, gamma-2,4-dichlorophenoxy-butyric acid, gamma-2-methyl-4-chlorophenoxy-butyric acid, alpha-2-methyl-4-chlorophenoxypropionic acid.

The substituted urea generally comprises a tri- or tetra- substituted urea such as N'-parachlorophenyl-N,N dimethylurea, N-butyl-N'-(3,4-dichlorophenyl)-N-methylurea, N'-parachlorophenyl-O,N,N-trimethylisourea, N'-p-chlorophenyl-N-methoxy-N-methylurea, N,N-dimethyl-N'-phenylurea.

The triazine herbicide generally comprises a compound of the formula: ##STR6## where X is a halogen, OY group or SY group, where Y is an alkyl group, and R⁷, R⁸, R⁹ and R¹⁰ are hydrogen or alkyl, such as 2-chloro-4,6-bisethylamino-1,3,5-triazine or 2-chloro-6-ethylamino-4-isopropylamino-1,3,5-triazine.

The phenol herbicide generally comprises 4,6-dinitro-ocresol or pentachlorophenol. The nitrile herbicide generally comprises 3,5-diiodo-4-hydroxy-benzonitrile, 3,5-dibromo-4-hydroxybenzo-nitrile or 2,6-dichlorobenzonitrile. The bipyridylium herbicide generally comprises 1,1'-dimethyl-4,4'-bipyridylium dichloride or 1,1'-ethylene-2,2'-bipyridylium dibromide. The substituted benzoic acid herbicide generally comprises 2,3,6-trichloro-benzoic acid or 2-methoxy-3,6-dichlorobenzoic acid. The halogenated aliphatic acid herbicide generally comprises trichloroacetic acid or 2,2-dichloropropionic acid. The carbomate herbicide generally comprises isopropyl N-(3-chlorophenyl) carbomate or 4-chloro-2-butynyl N-(3-chlorophenyl) carbomate. The thiocarbamate herbicide generally comprises S-ethyl N,N-dipropylthio-carbamate, S-ethyl N,N-diisobutylthiocarbamate and S-(2,3-dichloroally) N,N-diisopropylthiocarbomate. The chloroacetamide herbicide generally comprise N,N-diallyl-2-chloracetamide or N-isopropyl-2-chloroacetanilide. The diazine herbicide generally comprises 5-bromo-6-methyl-3-sec-butyluracil, 3-cyclohexyl-5,6-trimethyleneuracil or 1,2-dihydropyridazine-3,6-dione. The arsenic herbicide generally comprises a salt of methane arsonic acid or cacodylic acid. Other herbicides which may be used in such mixtures include aminotriazole,2,3-dichloro-1,4-naphthoquinone,4-amino-3,5,6-trichloropicolinic acid,2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline,6-chloro-2-trifluoromethylimidazo (4,5-b) pyridine and S,S,S-tributyl phosphorotrithioate.

A further embodiment of the invention comprises a process for the control of weeds, which comprises the use of a mixture of the benzofuranyl ester as identified and a second herbicide.

The ratio of the benzofuranyl ester to the second herbicide may vary over a wide range according to the particular compounds involved and the intended use. In general the ratio of benzofuranyl ester to second herbicide lies in the range 1:0.1 to 1:15.

These mixtures are of particular value in the control of weeds, and may be more effective and economical than the compounds used alone. In some cases synergism is observed.

In the use of the benzofuranyl esters as total herbicides, high rates of application, for example at least 10 pounds per acre, such as 10-25 pounds per acre, are required, unless the compounds are mixed with other active components, in which case the rate can be reduced.

In the use of the benzofuranyl esters as selective herbicides, the rate of application is much lower and may comprise for example 0.5-8 pounds per acre, such as 1-4 pounds per acre.

In the use of the benzofuranyl esters as plant growth regulants, low rates of application are required such as 0.1-4 pounds per acre, such as 0.5-1 pound per acre, according to the particular crop and use.

In the use of the esters as fungicides or insecticides for the treatment of plants, low rates of application will also be used such as 0.25-2 pounds per acre.

The rate of dilution of the active ingredient in the spray does not appear to be critical and may for example be based on volumes of 5-50 gallons per acre.

The esters may be used as plant growth regulants in standard ways. They can modify the natural growth characteristics of plants without killing them, and in particular are useful as growth retardants, e.g. of grass. Thus, they can be used on ornamental grass to retard growth so that less frequent mowing is required.

In the use of the esters as fungicides or insecticides for inanimate materials such as textiles the materials may be sprayed or dipped in a bath containing the esters. The treatment liquor suitably comprises an aqueous or organic solvent solution or suspension of the benzofuranyl ester containing for example 50-10,000 parts per million, and preferably 250-1,000 parts per million, of the benzofuranyl ester.

The benzofuranyl esters according to the present invention have been found of particular value in the control or growth retardation of annual and perennial grasses. Thus for example the benzofuranyl esters may be used for the control of couchgrass in crops such as brassica, potato, sugar beet and cereals such as maize, or for the control of cyperus in cotton.

The following examples are given to illustrate the present invention; parts and percentages are by weight unless otherwise indicated.

EXAMPLE 1

To a stirred solution of 2,3-dihydro-3,3-dimethyl-5-hydroxy-2-piperidino-benzofuran (640 parts) in dry pyridine (1000 parts) at 5°-10° C was added methanesulphonyl chloride (370 parts) over 1 hour. The mixture was stirred for a further 5 hours at about 10° C, then poured into water. The precipitated gum was washed with water (3 × 200 parts) by decantation, then triturated with ethanol (500 parts) when it set to a crystalline mass which was broken up, filtered, and the residue of crude ester was washed with aqueous ethanol (2:1) and sucked dry. Drying at 35° C in vacuo over phosphoric oxide gave 2,3-dihydro-3,3-dimethyl-2-piperidinobenzofuran-5-yl methanesulphonate (660 parts, 78%) m.p. 97°-8° C.

Crystallisation of a sample from ethanol gave pure 2,3-dihydro-3,3-dimethyl-2-piperidinobenzofuran-5-yl methanesulphonate, m.p. 101°-3° C.

Found: C, 59.15; H, 7.35; N, 4.10 C₁₆ H₂₃ NO₄ S requires: C, 59.06; H, 7.13; N, 4.31%

EXAMPLE 2

In a similar fashion were prepared the following compounds:

2,3-Dihydro-3,3-dimethyl-2-morpholinobenzofuran-5-yl methane-sulphonate, m.p. 111°-112° C (in 80% yield).

2,3-dihydro-3,3-dimethyl-2-(4-methylpiperazino) benzofuran-5-yl methanesulphonate, m.p. 98°-9° C.

2,3-dihydro-3-ethyl-2-morpholinobenzofuran-5-yl methanesulphonate, m.p. 104°-7° C.

2,3-dihydro-3-ethyl-2-piperidinobenzofuran-5-yl methanesulphonate, m.p. 85°-8° C.

1,2,3,4,4a,9b-hexahydro-4a-morpholinodibenzofuran-8-yl methane-sulphonate, m.p. 101°-3° C.

2,3-dihydro-3,3-dimethyl-2-(dimethylamino)benzofuran-5-yl methanesulphonate, m.p. 64°-65° C.

2,3-dihydro-3,3-dimethyl-2-pyrrolidino-4,6-dichloro-benzofuran-5-yl methanesulphonate, m.p. 94°-95° C.

2,3-dihydro-3,3,6,7-tetramethyl-2-pyrrolidinobenzofuran-5-yl methanesulphonate, m.p. 66°-67° C.

2,3-dihydro-3-hexyl-2-morpholinobenzofuran-5-yl methanesulphonate, m.p. 54°-57° C.

2,3-dihydro-3,3,6-trimethyl-2-morpholinobenzofuran-5-yl methanesulphonate, m.p. 134°-5° C.

2,3-dihydro-3,3-dimethyl-2-morpholino-6-methoxybenzofuran-5-yl methanesulphonate, m.p. 126°-8° C.

2,3-dihydro-3,3-dimethyl-2-morpholino-6-isopropylbenzofuran-5-yl methanesulphonate, m.p. 102°-3° C.

2,3-dihydro-3,3-dimethyl-2-morpholino-4-acetylbenzofuran-5-yl methanesulphonate, m.p. 156°-8° C.

2,3-dihydro-3,3-dimethyl-2-morpholino-6-chlorobenzofuran-5-yl methanesulphonate, m.p. 136°-8° C.

2,3-dihydro-3,3-dimethyl-2-morpholino-4,6-dichloro-benzofuran-5-yl methanesulphonate, m.p. 163°-5° C.

2,3-dihydro-3,3-dimethyl-2-morpholinobenzofuran-5-yl ethanesulphonate, m.p. 66°-70° C.

2,3-dihydro-3,3-dimethyl-2-morpholinobenzofuran-5-yl butanesulphonate, m.p. 62°-64° C.

2,3-dihydro-3,3-dimethyl-2-morpholinobenzofuran-5-yl 3-methoxypropanesulphonate, m.p. 73°-74° C.

2,3-dihydro-3,3-dimethyl-2-morpholinobenzofuran-5-yl chloromethanesulphonate, m.p. 130°-2° C.

2,3-dihydro-3,3-dimethyl-2-(4-methylpiperazino) benzofuran-5-yl ethanesulphonate, m.p. 82°-84° C.

2,3-dihydro-3,3-dimethyl-2-pyrrolidinobenzofuran-5-yl propanesulphonate, undistillable liquid.

2,3-dihydro-3,3-dimethyl-2-pyrrolidinobenzofuran-5-yl ethanesulphonate, undistillable oil.

2,3-dihydro-3,3-dimethyl-2-pyrrolidinobenzofuran-5-yl 2,2-dichloropropionate, undistillable oil.

2,3-dihydro-3-3-dimethyl-2-piperidinobenzofuran-5-yl 2,2-dichloropropionate, undistillable oil.

2,3-dihydro-3,3-dimethyl-2-morpholinobenzofuran-5-yl p-toluenesulphonate, m.p. 108° C.

2,3-dihydro-3,3-dimethyl-2-piperidinobenzofuran-5-yl p-toluenesulphonate, m.p. 98° C.

2,3-dihydro-3-ethyl-2-(4-methylpiperazino)benzofuran-5-yl methanesulphonate, m.p. 93°-94° C.

2,3,3a,8b-tetrahydro-3a-morpholino-1H-cyclopenta (b)benzofuran-7-yl methanesulphonate, m.p. 144°-6° C.

2,3-dihydro-3,3-dimethyl-2-morpholino-6,7-dichlorobenzofuran-5-yl methanesulphonate, m.p. 135°-136° C.

2,3-dihydro-3,3,6,7-tetramethyl-2-morpholinobenzofuran-5-yl methanesulphonate, m.p. 102°-103° C.

EXAMPLE 3

A cold suspension of 2,3-dihydro-3,3-dimethyl-5-hydroxy-2-pyrrolidino-benzofuran (18.5 parts) in dry ether (150 parts) and triethylamino (9.3 parts) was treated with methanesulphonyl chloride (10.5 parts) added all at once. After 0.75 hours the mixture was filtered and the filtrate was diluted to opalescence with petrol and filtered through kieselguhr. The filtrate was then evaporated to half volume and diluted with petrol giving white crystals (7.5 parts), m.p. 79°-81° C of 2,3-dihydro-3,3-dimethyl-2-pyrrolidinobenzofuran-5-yl methanesulphonate.

Found: C, 57.55; H, 6.70; N, 4.30% C₁₅ H₂₁ NO₄ S requires: C, 57.86; H, 6.80; N, 4.30%

EXAMPLE 4

A suspension of 2,3-dihydro-3,3-dimethyl-2-morpholinobenzofuran-5-yl methanesulphonate (product of Example 2) (24.9 parts) in water (50 parts) and hydrochloric acid (22.4 parts) was rapidly heated to 90°-100° C and then cooled after 2 minutes. The crude product was extracted into ether (3 × 60 parts) and the extracts washed with water (2 × 50 parts), dried with sodium sulphate and evaporated to leave a gum which crystallised to give 2,3-dihydro-3,3-dimethyl-2-hydroxybenzofuran-5-yl methanesulphonate, m.p. 69°-72° C (16 parts)

EXAMPLE 5

The following were prepared by a similar method to that described in Example 4.

2,3-dihydro-3,3-dimethyl-2-hydroxy-6-methoxybenzofuran-5-yl methanesulphonate, m.p. 114°-6° C.

2,3-dihydro-3,3-dimethyl-2-hydroxy-6-isopropylbenzofuran-5-yl methanesulphonate, m.p. 103°-5° C.

2,3-dihydro-3,3,6,7-tetramethyl-2-hydroxybenzofuran-5-yl methanesulphonate, m.p. 109°-110° C.

2,3-dihydro-3,3-dimethyl-2-hydroxybenzofuran-5-yl ethane sulphonate, oily liquid.

EXAMPLE 6

A solution of crude 2,3-dihydro-3,3-dimethyl-2-hydroxybenzofuran-5-yl methanesulphonate (7.8 parts) in methanol (80 parts) containing sulphuric acid (2 drops) was boiled under reflux for one hour and then cooled. The solution was then neutralised with triethylamine and then evaporated to about quarter its volume. Water (10 parts) was then added to precipitate 2,3-dihydro-3,3-dimethyl-2-methoxybenzofuran-5-yl methanesulphonate, m.p. 69°-70° C.

Found: C, 53.15; H, 5.75 C₁₂ H₁₆ O₅ S requires: C, 52.94; H, 5.92%

EXAMPLE 7

Using a similar method to that of Example 6, the following were prepared:

2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl methanesulphonate, m.p. 70°-72° C.

2,3-dihydro-3,3-dimethyl-2-allyloxybenzofuran-5-yl methanesulphonate, m.p. 51°-52° C.

2,3-dihydro-3,3-dimethyl-2-(2-methoxyethoxy) benzofuran-5-yl methanesulphonate, m.p. 50°-53° C.

2,3-dihydro-3,3-dimethyl-2-ethylthiobenzofuran-5-yl methanesulphonate, liquid.

2,3-dihydro-3,3,6,7-tetramethyl-2-ethoxybenzofuran-5-yl methanesulphonate, m.p. 76°-8° C.

2,3-dihydro-3,3-dimethyl-2-isopropoxybenzofuran-5-yl methanesulphonate, m.p. 54°-56° C.

2,3-dihydro-3,3-dimethyl-2-propargyloxybenzofuran-5-yl methanesulphonate, liquid.

2,3-dihydro-3,3-dimethyl-2-(4-chloro-2-butynyloxy) benzofuran-5-yl methanesulphonate.

2,3-dihydro-3,3-dimethyl-2-(p-nitrophenoxy) benzofuran-5-yl methanesulphonate, m.p. 160°-3° C.

2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl 3-methoxy-propanesulphonate, liquid.

2,3-dihydro-3,3-dimethyl-2-(2-chloroethoxy) benzofuran-5-yl methanesulphonate, liquid.

2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl ethane-sulphonate, liquid.

2,3-dihydro-3,3-dimethyl-2-methoxybenzofuran-5-yl ethanesulphonate, liquid.

2,3-dihydro-3,3-dimethyl-2-isopropoxybenzofuran-5-yl ethanesulphonate, liquid.

2,3-dihydro-3,3-dimethyl-2-allyloxybenzofuran-5-yl ethanesulphonate, liquid.

2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl butanesulphonate, m.p. 57°-9° C.

EXAMPLE 8

To a cooled solution of 2-hydroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (8.0 parts) in dry pyridine (42 parts) was added benzoyl chloride (4.75 parts) at such a rate that the temperature did not exceed 10° C. After one hour the mixture was poured into a slight excess of dilute hydrochloric acid. The product was extracted with ether and the ethereal solution washed, dried with sodium sulphate and evaporated to give an oil which solidified on scratching. The solid was recrystallised from a mixture of benzene and light petroleum to give 2-benzoyloxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (5.1 parts), melting point 102°-104° C.

EXAMPLE 9

Using an analogous method to that described in Example 8 the following were prepared:

2-isobutyryloxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate, m.p. 77°-79° C.

2-acetoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate, m.p. 84°-85° C.

2,3-dihydro-3,3-dimethyl-2-(phenoxyacetoxy)benzofuran-5-yl methanesulphonate, m.p. 103°-5° C.

2,3-dihydro-3,3-dimethyl-2-benzoyloxybenzofuran-5-yl ethanesulphonate, m.p. 101°-3° C.

2,3-dihydro-3,3-dimethyl-2-acetoxybenzofuran-5-yl ethanesulphonate, m.p. b 56°-8° C.

EXAMPLE 10

A solution of 2-hydroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (5 parts) in ether (85 parts) was treated with triethylamine (2.2 parts) and acetic anhydride (2.3 parts) at 10° C and allowed to stand for 4 hours. The solution was then diluted with light petroleum (80 parts) and filtered. The filtrate was evaporated to give an oil which solidified. This was recrystallised from a mixture of chloroform and petroleum to give 2-acetoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (2.5 parts), melting point 84°-85° C.

EXAMPLE 11

To a solution of 2-hydroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (10 parts) in water (100 parts) containing sodium hydroxide (15 parts) was slowly added acetic anhydride (10 parts) with cooling to keep the temperature below 10° C. An oil separated which solidified on scratching. This was filtered off, washed with water, dried and recrystallised from 90% aqueous ethanol to give 2-acetoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate, melting point 84°-85° C.

EXAMPLE 12

2-ethoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (7 parts) was treated with a mixture of acetic anhydride (20 parts) and sulphuric acid (0.6 parts) and left at 50° C for two hours. The solution was then poured into an excess of ice and sodium bicarbonate. An oil precipitated which solidified and was filtered off and recrystallised from 90% aqueous ethanol to give 2-acetoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (6.6 parts), melting point 83°-85° C.

EXAMPLE 13

A solution of 2-hydroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (5 parts) in ether (85 parts) was treated at 10° C with triethylamine (2.2 parts) and methanesulphonyl chloride (2.2 parts) and allowed to stand for 4 hours. The solution was then diluted with light petroleum (80 parts) and filtered through alumina. The filtrate was evaporated to dryness in vacuo and the residual oil solidified. Recrystallisation from a mixture of benzene and light petroleum gave 2,3-dihydro-3,3-dimethylbenzofuran-2,5-ylene bis-methanesulphonate, melting point 56°-58° C.

EXAMPLE 14

To a solution of 2-hydroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (12 parts) in ether (46 parts) was added methyl isocyanate (4.5 parts) and triethylamine (0.3 parts). The solution was left at room temperature for two hours and the solvent evaporated off. The crude product was recrystallised from a mixture of benzene and light petroleum to give 2-methylcarbamoyloxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate, melting point 126°-127° C.

Found: C, 48.55; H, 5.15; N, 4.65 C₁₃ H₁₇ NO₆ S requires: C, 49.52; H, 5.44; N, 4.44%

EXAMPLE 15

The following was prepared by a similar method to that described in Example 14.

2,3-dihydro-3,3-dimethyl-2-(m-chlorophenylcarbamoyloxy) benzofuran-5-yl methanesulphonate, m.p. 142°-3° C.

EXAMPLE 16

A solution of 2-hydroxy-2,3-dihydro-3,3-dimethyl benzofuran-5-yl methane sulphonate in ether was reacted with triethylamine and methyl chloroformate. The product was worked up to separate 2,3-dihydro-3,3-dimethyl-5-methane sulphonyloxy benzofuran-2-yl methylcarbonate, melting point 88°-9° C.

In a similar way, using ethyl chloroformate in place of methyl chloroformate there was obtained 2,3-dihydro-3,3-dimethyl-5-methane sulphonyloxy benzofuran-2-yl ethyl carbonate, melting point 85°-7° C.

EXAMPLE 17

The following were prepared by a similar method to that described in Example 16.

2,3-dihydro-3,3-dimethyl-5-methanesulphonyloxybenzofuran-2-yl 4-chloro-2-butynyl carbonate, m.p. 70°-74° C.

2,3-dihydro-3,3-dimethyl-5-methanesulphonyloxybenzofuran-2-yl 2-methoxyethyl carbonate, m.p. 50°-52° C.

2,3-dihydro-3,3-dimethyl-5-methanesulphonyloxybenzofuran-2-yl isoamyl carbonate, m.p. 59°-61° C.

2,3-dihydro-3,3-dimethyl-5-ethanesulphonyloxybenzofuran-2-yl ethyl carbonate, m.p. 91°-3° C.

EXAMPLE 18

A solution of 2-hydroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (20 parts), tertiary-butyl hydroperoxide (7 parts) and 1,4-dihydroxybenzene (0.5 parts) in benzene (800 parts) containing sulphuric acid (0.5 parts) was gently boiled under reflux for two hours. After cooling, triethylamine (1 part) was added and the filtered solution was concentrated below 20° C in vacuo, to give 2-tert-butyl-peroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (10 parts, 40% yield) as a yellow gum with infra-red and nuclear magnetic resonance spectra consistent with the assigned structure.

Analsysis: Found: C, 54.60; H, 5.95

C₁₅ H₂₂ O₆ S requires : C, 54.57; H, 6.67%

EXAMPLE 19

A solution of 2-hydroxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate (20 parts) in warm acetic acid (200 parts) was treated with 200 parts of a 20% aqueous solution of chromic oxide. After about 15 seconds the mixture was poured into water and the solution extracted with ether. The extracts were thoroughly washed with aqueous sodium bicarbonate, then dried and the solvent evaporated to give 2-oxo-2,3-dihydro-3,3-dimethyl-benzofuran-5-yl methanesulphonate (14 parts, 70% yield), melting point 120°-120° C after recrystallization from benzene-petroleum.

Analysis: Found: C, 51.80; H, 4.95

C₁₁ H₁₂ O₂ S requires : C, 51.56; H4.72%

EXAMPLE 20

The compounds listed in the table below were each formulated as an attaclay/sand dust and incorporated in John Innes I potting compost at a rate of 130 or 26 parts per million weight/volume active ingredient to soil (respectively approximately 50 or 10 lbs. active ingredient per acre cultivated to a depth of 2 inches). The treated soil samples were placed in anodised aluminum pans, 71/2 ins. long × 33/4 ins. wide × 2 ins. deep. Seeds of peas (Pisum sativum), mustard (Sinapis alba), linseed (Linum usitatissmum), maize (Zea mays), oats (Avena sativa) and ryegrass (Lolium sp.) were sown in the treated soil, one species per pan, watered and placed in a controlled environment room (temperature 22° C, relative humidity 65-85%, artifical illumination 1200 foot-candles for 14 hours per day) for 21 days. The plants were then visually assessed for any growth regulatory or herbicidal effects, all differences from untreated controls being scored on a scale from 0 to 100 in which 0 signifies no effect and 100 signifies complete suppression. The activities against each species are tabulated below.

    __________________________________________________________________________                      Rate   Mus-                                                                              Lin-      Rye-                                      Compound         (lb/a)                                                                             Peas                                                                              tard                                                                              seed                                                                              Maize                                                                              Oats                                                                              grass                                     __________________________________________________________________________     2-tert-butylperoxy-                                                            2,3-dihydro-3,3-di-                                                                             10  55 90 84 100 100                                                                               99                                        methylbenzofuran-5-yl                                                          methanesulphonate                                                              2-oxo-2,3-dihydro-                                                             3,3-dimethylbenzofuran-                                                                         50  97 98 94 100 100                                                                               98                                        5-yl-methanesulphonate                                                         2,3-dihydro-3,3-dimethyl-                                                      benzofuran-2,5-ylene                                                                            10  98 97 97 98  99 98                                        bis-methanesulphonate                                                          2-acetoxy-2,3-dihydro-3,                                                       3-dimethylbenzofuran-5-yl                                                                       50  100                                                                               100                                                                               99 99  100                                                                               100                                       methanesulphonate                                                                               10  75 80 90 98  98 95                                        2,3-dihydro-3,3-dimethyl-5-                                                    methanesulphonyloxy-benzofuran-                                                2-yl ethyl carbonate                                                                            10  70 60 75 100 98 99                                        2-benzoyloxy-2,3-dihydro-                                                      3,3-dimethylbenzofuran-                                                                         50  99 95 99 98  100                                                                               100                                       5-yl methanesulphonate                                                         2-isobutyryloxy-2,3-                                                           dihydro-3,3-dimethyl-                                                                           50  95 95 98 99  100                                                                               100                                       benzofuran-5-yl                                                                methanesulphonate                                                              2,3-dihydro-3,3-dimethyl                                                       2-piperidino-benzofuran-                                                                        50  85 99 99 99  100                                                                               100                                       5-yl methanesulphonate                                                         2,3-dihydro-3,3-dimethyl                                                       2-morpholino-benzofuran-                                                                        50  65 85 94 99  100                                                                               90                                        5-yl methanesulphonate                                                         2,3-dihydro-3,3-dimethyl-                                                      2-ethoxybenzofuran-5-                                                                           50  100                                                                               100                                                                               100                                                                               100 100                                                                               100                                       yl methanesulphonate                                                           2,3-dihydro-3,3-dimethyl-                                                      2-pyrrolidinobenzofuran-                                                                        10  70 70 100                                                                               98  100                                                                               91                                        5-yl methanesulphonate                                                         2,3-dihydro-3,3-dimethyl-                                                      2-(4-methylpiperazino)                                                                          50  100                                                                               100                                                                               100                                                                               100 100                                                                               100                                       benzofuran-5-yl methane-                                                       sulphonate                                                                     2,3-dihydro-3-ethyl-2-                                                         (4-methylpiperazino)-                                                                           50  25 85 65 100 100                                                                               98                                        benzofuran-5-yl methane                                                        sulphonate                                                                     2,3-dihydro-3,3-dimethyl-                                                      2-methoxybenzofuran-5-                                                                          50  100                                                                               100                                                                               100                                                                               100 100                                                                               100                                       yl methanesulphonate                                                           2,3-dihydro-3,3-dimethyl-                                                      2-isopropoxybenzofuran-                                                                         50  80 100                                                                               98 99  100                                                                               85                                        5-yl methanesulphonate                                                         2,3-dihydro-3,3-dimethyl-                                                      2-allyloxybenzofuran-5-                                                                         50  90 100                                                                               100                                                                               88  97 80                                        yl methanesulphonate                                                           2,3-dihydro-3,3-dimethyl-                                                      2-(2-methoxyethoxy)                                                                             50  90 98 100                                                                               92  97 80                                        benzofuran-5-yl methane                                                        sulphonate                                                                     2,3-dihydro-3,3-dimethyl-                                                      2-propargyloxybenzofuran-                                                                       50  80 100                                                                               100                                                                               100 98 90                                        5-yl methanesulphonate                                                         2,3-dihydro-3,3-dimethyl-2-                                                    morpholino-benzofuran-5-yl                                                     chloromethanesulphonate                                                                         50  70 100                                                                               100                                                                               100 97 90                                        2,3-dihydro-3,3-dimethyl                                                       2-hydroxybenzofuran-5-yl                                                                        10  85 80 96 100 100                                                                               99                                        methanesulphonate                                                              2,3-dihydro-3,3-dimethyl-                                                      2-morpholinobenzofuran-5-                                                                       30  100                                                                               100                                                                               100                                                                               99  100                                                                               100                                       yl ethanesulphonate                                                            2,3-dihydro-3,3-dimethyl-2-                                                    ethoxybenzofuran-5-yl                                                                           50  90 100                                                                               98 100 100                                                                               97                                        ethanesulphonate                                                               2,3-dihydro-3,3-dimethyl-                                                      2-morpholino-6-chlorobenzo-                                                                     50  91 99 85 100 100                                                                               90                                        furan-5-yl methanesulphonate                                                   2,3-dihydro-3,3-dimethyl-2-                                                    (dimethylamino)benzofuran-5-                                                                    10  60 70 90 100 98 100                                       yl methanesulphonate                                                           __________________________________________________________________________

EXAMPLE 21

Seeds of peas, mustard, linseed, ryegrass, sugarbeet and oats were sown in anodised aluminum pans, 71/2 long × 33/4 wide × 2 inches deep containing John Innes No. 1 potting compost. They were then watered and placed in a controlled environment room (22° C, 65-85% relative humidity and 14 hours/day artifical illumination at 1200 foot candles). Fourteen days after sowing, the seedlings were sprayed with 50% aqueous acetone solutions of the compounds listed in the table below at rates equivalent to 10 lbs. of active ingredient in 80 gallons per acre.

After seven days' growth in a controlled environment room the plants were visually assessed for herbicidal response by comparison with untreated controls. The table below gives the herbicidal activity on a 0-100 scale in which 0 represents no effect and 100 represents complete kill.

    ______________________________________                                                                                Su-                                                           Mus-   Lin- Rye  gar                                     Compound       Peas   tard   seed grass                                                                               beet Oats                               ______________________________________                                         2,3-dihydro-3,3-dimethyl-2-                                                    piperidino-5-benzofuranyl                                                                     45     65     65   70   24   75                                 methanesulphonate                                                              2,3-dihydro-3,3-dimethyl-2-                                                    morpholino-5-benzofuranyl                                                                     45     65     65   72   30   75                                 methanesulphonate                                                              2,3-dihydro-3,3-dimethyl-2-                                                    pyrrolidino-5-benzofuranyl                                                                    90     95     95   95   35   90                                 methanesulphonate                                                              2,3-dihydro-3,3-dimethyl-2-                                                    (4-methylpiperazino)-                                                                         45     48     65   60   20   75                                 5-benzofuranyl                                                                 methanesulphonate                                                              2,3-dihydro-3-ethyl-2-                                                         piperidino-5-benzo-                                                                           30     45     32   65   20   85                                 furanyl methane-                                                               sulphonate                                                                     2,3-dihydro-3-ethyl-2-                                                         morpholino-5-benzofuranyl                                                                     35     65     65   65   20   85                                 methanesulphonate                                                              ______________________________________                                    

EXAMPLE 22

Aqueous acetone solutions containing 2000 parts per million (ppm.) of the compounds listed in the table below together with 125 ppm. of a wetting agent were sprayed on to the leaves of young potato plants having seven fully expanded leaves, until the plants were completely wetted. After 24 hours, the treated plants were inoculated with sporangia of the disease potato blight (Phytophthora infestans). The plants where then placed in a water saturated atmosphere for 24 hours and then kept in a controlled environment room (Temperature 18° C, relative humidity 80-90%) for five days. At the end of this period, the percentage disease control was measured by comparison with control plants sprayed with a solution of wetting agent alone. Results were as follows:

    ______________________________________                                                                       Con-                                             Compound                      trol                                             ______________________________________                                         2,3-dihydro-3,3-dimethyl-2-pyrrolidinobenzofuran-5-yl                          methanesulphonate             75%                                              2,3-dihydro-3-ethyl-2-piperidinobenzofuran-5-yl                                methanesulphonate             90%                                              2,3-dihydro-3-ethyl-2-(4-methylpiperazino)benzofuran-                          5-yl methanesulphonate        80%                                              ______________________________________                                    

EXAMPLE 23

A wettable powder formulation was made up by grinding the following ingredients:

    ______________________________________                                         2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl                               methanesulphonate             20%                                              Diatomaceous earth            70%                                              Hoe S2/268 (wetting/dispersing agent)                                                                        5%                                               Dyapol PT (dispersing agent)  5%                                               ______________________________________                                    

(Hoe S2/268 contains a sodium salt of a sulphated fatty alcohol/ethylene oxide condensate. Dyapol PT is the sodium salt of a sulphonated cresol/urea/formaldehyde condensate).

EXAMPLE 24

A wettable powder formulation was made up by grinding the following ingredients:

    ______________________________________                                         2,3-dihydro-3,3-dimethyl-2-piperidinobenzofuran-                               5-yl methanesulphonate        20%                                              China clay                    70%                                              Hoe S1/263 (wetting/dispersing agent)                                                                        10%                                              ______________________________________                                    

(Hoe S1/263 contains a mixture of a fatty alcohol/ethylene oxide condensation product and an ethylene oxide/propylene oxide block copolymer).

EXAMPLE 25

An aqueous suspension of 2-ethoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methane sulphonate was sprayed at a rate of 2 lbs per acre in 40 gallons on a plot in which cotton had been sown the previous day. After six weeks the cotton seedlings had developed with less than 15% of the weed infestation of unsprayed control plots in which the main weeds were Nutsedge (Cyperus rotundus) and Crabgrass (Digitaria sanguinalis).

EXAMPLE 26

1 ml. aliquots of acetone solutions of 2,3-dihydro-3,3-dimethyl-2-morpholino-benzofuran-5-yl methanesulphonate, 2,3-dihydro-3,3-dimethyl-2-(4-chloro-2-butynyloxy)benzofuran-5-yl methanesulphonate and 2,3-dihydro-3,3-dimethyl-5-methane-sulphonyloxybenzofuran-2-yl 4-chloro-2-butynyl carbonate were applied to 9 cm. diameter filter papers placed in the bottom of 9 cm. diameter glass dishes at concentrations such as to produce deposits equivalent to 1000, 300 and 100 mg/sq. ft. The treated filter papers were then infested with adult house flies (musca domestica), covered with a glass lid and kept at 20° C for 24 hours. At the end of this time all the flies were found to be dead.

EXAMPLE 27

An experiment was conducted on bent/fescue mixture grass in summer. The grass had not been treated with a fertilizer or chemical within the previous year. 2.8 Kg per ha of 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl methanesulphonate was sprayed on in water. Whereas untreated grass used as a control grew to a mean height of 6 cm in 4-5 weeks, the treated grass took over 11 weeks. The growth retardant effect is apparent.

It is to be noted that the benzofuranyl esters according to the invention where R⁴ is hydroxy, in aqueous alkaline solution form the corresponding open chain compound by opening of the furan ring at the oxygen atom; these derivatives posses similar properties to the benzofuranyl esters and are also embraced in the present invention. The derivatives are in the form of a salt of the alkali; the alkali used is preferably an alkali metal hydroxide, and the salt is an alkali metal salt. 

We claim:
 1. A herbicidal composition comprising a herbicidal amount of a benzofuranyl compound of the formula ##STR7## wherein R is a member selected from the group consisting of alkyl of 1 to 8 carbon atoms, alkenyl of 2 to 4 carbon atoms, monochloro alkenyl of 2 to 4 carbon atoms, alkynyl of 2 to 6 carbon atoms, monochloro alkynyl of 2 to 6 carbon atoms, alkoxyalkyl of 2 to 8 carbon atoms; R¹ is hydrogen or alkyl of 1 to 4 carbon atoms; R² and R³ are the same or different and are hydrogen or alkyl of 1 to 4 carbon atoms; R⁵ is alkyl of 1 to 4 carbon atoms or monochloro alkyl of 1 to 4 carbon atoms; and R⁴, R⁶ and R⁷ are the same are different and are hydrogen, halogen or alkyl of 1 to 4 carbon atoms, with an inert carrier or wetting agent.
 2. A composition as claimed in claim 1 which contains a wetting agent.
 3. A composition as claimed in claim 2 wherein R is alkyl of 1 to 8 carbon atoms.
 4. A composition as claimed in claim 2 wherein R⁵ is alkyl of 1 to 4 carbon atoms.
 5. A composition as claimed in claim 2 wherein R² and R³ are the same or different and are alkyl of 1 to 4 carbon atoms.
 6. A composition as claimed in claim 2 wherein R⁴, R⁶ and R⁷ are hydrogen.
 7. A composition as claimed in claim 2 wherein R is alkyl of 1 to 8 carbon atoms, R⁵ is alkyl of 1 to 4 carbon atoms, R² and R³ are the same or different and are alkyl of 1 to 4 carbon atoms and R⁴, R⁶ and R⁷ are hydrogen.
 8. A composition as claimed in claim 2 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-methoxybenzofuran-5-yl methanesulphonate.
 9. A composition as claimed in claim 2 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-isopropoxybenzofuran-5-yl methanesulphonate.
 10. A composition as claimed in claim 2 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-allyloxybenzofuran-5-yl methanesulphonate.
 11. A composition as claimed in claim 2 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-(2-methoxyethoxy)benzofuran-5-yl methanesulphonate.
 12. A composition as claimed in claim 2 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-propargyloxybenzofuran-5-yl methanesulphonate.
 13. A composition as claimed in claim 2 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl ethanesulphonate.
 14. A composition as claimed in claim 2 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl methanesulphonate.
 15. A method of combating weeds at a locus infested or liable to be infested with them, comprising applying to the locus a weed-combating amount of a composition claimed in claim
 1. 16. A method as claimed in claim 15 wherein weeds are combated in a crop.
 17. A method as claimed in claim 16 wherein the crop is sugar beet.
 18. A method as claimed in claim 17 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl methanesulphonate.
 19. A method as claimed in claim 15 wherein R is alkyl of 1 to 8 carbon atoms.
 20. A method as claimed in claim 15 wherein R⁵ is alkyl of 1 to 4 carbon atoms.
 21. A method as claimed in claim 15 wherein R² and R³ are the same or different are are alkyl of 1 to 4 carbon atoms.
 22. A method as claimed in claim 15 wherein R⁴, R⁵ and R⁶ are hydrogen.
 23. A method as claimed in claim 15 wherein R is alkyl of 1 to 8 carbon atoms, R⁵ is alkyl of 1 to 4 carbon atoms, R² and R³ are the same or different and are alkyl of 1 to 4 carbon atoms and R⁴, R⁶ and R⁷ are hydrogen.
 24. A method as claimed in claim 15 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-methoxybenzofuran-5-yl methanesulphonate.
 25. A method as claimed in claim 15 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-isopropoxybenzofuran-5-yl methanesulphonate.
 26. A method as claimed in claim 15 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-allyloxybenzofuran-5-yl methanesulphonate.
 27. A method as claimed in claim 15 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-(2-methoxyethoxy)benzofuran-5-yl methanesulphonate.
 28. A method as claimed in claim 15 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-propargyloxybenzofuran-5-yl methanesulphonate.
 29. A method as claimed in claim 15 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl ethanesulphonate.
 30. A method as claimed in claim 15 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl methanesulphonate.
 31. A method as claimed in claim 15 wherein the composition contains a wetting agent.
 32. A plant growth regulant composition for effecting growth retardation comprising a plant growth regulating amount of a benzofuranyl compound of the formula ##STR8## wherein R is a member selected from the group consisting of alkyl of 1 to 8 carbon atoms, alkenyl of 2 to 4 carbon atoms, monochloro alkenyl of 2 to 4 carbon atoms, alkynyl of 2 to 6 carbon atoms, monochloro alkynyl of 2 to 6 carbon atoms, alkoxyalkyl of 2 to 8 carbon atoms; R¹ is hydrogen or alkyl of 1 to 4 carbon atoms; R² and R³ are the same are different and are hydrogen or alkyl of 1 to 4 carbon atoms; R⁵ is alkyl of 1 to 4 carbon atoms or monochloro alkyl of 1 to 4 carbon atoms; and R⁴, R⁶ and R⁷ are the same or different and are hydrogen, halogen or alkyl of 1 to 4 carbon atoms, with an inert carrier or wetting agent.
 33. A composition as claimed in claim 32 which contains a wetting agent.
 34. A composition as claimed in claim 33 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl methanesulphonate.
 35. A method of modifying plant growth by means of retardation which comprises applying to the plant or the soil surrounding the plant a plant growth regulant amount of a composition claimed in claim
 32. 36. A method as claimed in claim 35 wherein the composition contains a wetting agent.
 37. A method as claimed in claim 35 wherein the benzofuranyl compound is 2,3-dihydro-3,3-dimethyl-2-ethoxybenzofuran-5-yl methanesulphonate. 